Bought 60mm Macro and I'm getting into Macro , would like to get more magnification, so in a near future I will buy set of Kenko ext. tubes.

What magnification I can get , and what will be the working distance with those tubes?
Any change (like bokeh, DOF) should I expect?

It's possible to use that combo without tripod ( don't like to use it for macro shots).
Any other tips?
Thank you.
--
In an ocean of absurdity, fins still are needed
Regards,
Andy
http://www.pbase.com/sobax